The present invention generally relates to a head positioning mechanism for a magnetic disk device provided with a micro tracking actuator which uses a magnetic force, and to a drive control method therefor. More particularly, the present invention relates to a head positioning mechanism for use in a magnetic disk device, which is used for precisely fixing the positional relation between a carriage and a supporting spring when performing a seeking operation of moving a magnetic head to a target track of a magnetic disk medium (hereunder referred to as a magnetic disk), and to a drive control method therefor.
In the case of a conventional magnetic disk device, a seeking operation of moving a magnetic head to a target track of a magnetic disk is performed by an actuator. The magnetic head is moved to a target track in a control mode. Further, the conventional magnetic disk device is adapted so that the magnetic head is held on the target track in a position control mode after the magnetic head reaches the target track.
In the case of such a conventional magnetic disk device, the movement of a magnetic head is performed by using a carriage and a supporting spring which are connected to an actuator. However, recently, as the storage capacity of a magnetic disk is considerably increased, an actuator is required to have high accuracy of positioning of a magnetic head. To enhance the accuracy of positioning of a magnetic head, there has been proposed a system which uses a micro tracking actuator for performing a seeking operation of moving a magnetic head by a minute distance.
For example, a magnetic disk device employing a minute displacement generating element as the micro tracking actuator has been known as such a conventional system. In the case of this conventional system, when performing a (high-precision) seeking operation of moving a magnetic head to a target track of a magnetic head, a (coarse) seeking operation of moving the magnetic head to the target track is first performed. Then, the actuator is stopped. Subsequently, the positioning of the magnetic head by means of the minute displacement generating element according to a position error signal is performed as a precise seeking operation of moving the magnetic head.
Moreover, there has been another conventional magnetic disk device provided with a micro tracking actuator using a magnetic force. This magnetic disk device is provided with a carriage and a supporting spring.
However, in the case of the former magnetic disk device using the minute displacement element, a high voltage is necessary for driving the element. Further, the minute displacement generating element has drawbacks in that the long-term reliability thereof is low and thus, the practicality thereof is low.
Furthermore, in the latter case, namely, in the case of the micro tracking actuator using a magnetic force, the supporting spring is vibrated owing to the seeking operation. Thus, such a micro tracking actuator has a drawback in that it is difficult to achieve the complete fixation thereof.